Sarasas

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Wheeee

October 15, 2007

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Grattis till mig idag!

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The COVID-19 testing delays in Sweden as a prime example of queueing theory

One branch of statistics is Queueing Theory . It is an attempt to predict the behaviour of a system as a function of the inflow and the outflow. As examples you typically have either bank tellers or buffered network routers, but now we have an excellent example in front of us in the Swedish news. One tool in the fight against the COVID-19 pandemic is testing. By tracking who is infected we can better prevent it from spreading to others, but for that to work, we need the test done and the test result returned before the person has already spread the virus. In Sweden we expanded the testing capactity slowly but steadily during May and June and all through this process the waiting time, if you were allowed to get a test, was short. As vacations ended and autumn colds came, that changed. Now people may have to wait for 4 days to get a test done and for another 4 days before the result is returned, despite labs working more efficiently and faster than ever before and returning 50% more

A better algorithm for paths with gradients

To code example → This article will present an algorithm, and code, to create the effect in the image below, where a gradient follows along a shape, a "path" in SVG parlance. This is not the first attempt at solving this problem, thus the "better" part of the title, but I found earlier available code to have some very specific flaws, especially with complex paths. By default, SVG provides for two ways to do gradients, linearGradient and radialGradient. As the names imply, the gradient for those either follows a straight line or a circular radius. In particular, there is no way in SVG to have a gradient evolve along a path. Linear Gradient Radial Gradient If you try to apply either gradient to a path, you will see that it is just applied along a line or along a ra

How big is Linköping compared to Manhattan?

Manhattan is massive in a lot of ways. Massive skyscrapers, a massive throng of people moving around it, but how large is it really to a random Swedish small city, when looking at area alone. To compare the two areas I went out of the way and created a site that allows you to view two maps side by side, in the exact same scale. This is a little bit harder than it might seem since map services have different resolutions depending on latitude, so everything looks smaller near the equator. It's the old Mercator projection flaw that West Wing made famous . Realizing that you needed to use different zoom levels at different latitudes was not enough as there is a fixed set of available zoom levels on most (all?) map vendors. Therefore I also had to use fractions of zoom levels, i.e. do a bit of stretching or compressing to match more closely. This did unfortunately result in a bit of fuzziness, but not more than acceptable. Example (mobile screen): Manhattan is darker gray but it&

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